The present invention relates to the field of the connection between the floor structure and the hull structure, in an aircraft.
The structure 10 of an aircraft comprises in particular the hull structure and the floor structure. FIG. 1 shows an example of a connection according to the prior art, between a hull structure 11 and a floor structure 12.
An orthonormal reference system (Oxyz) is defined.
The axis Ox corresponds to the longitudinal axis Ox of the aircraft. The front and the rear of the aircraft are defined along this axis Ox. The front of the aircraft corresponds to the nose of the aircraft, where the cockpit is located. The rear of the aircraft corresponds to the tail of the aircraft, where the vertical stabilizer is generally located. In what follows, it is assumed that, in normal flight conditions, the aircraft moves along the axis Ox, along a vector oriented from the rear towards the front of the aircraft.
The axis Oz corresponds to the vertical axis, when the aircraft is on the ground, in the parking position.
The axis Oy defines with the axis Ox a horizontal plane, when the aircraft is on the ground, in the parking position. The axis Oy corresponds to the transverse axis of the aircraft.
The hull structure 11 comprises in particular a set of frames 11A, forming stiffeners which are transverse relative to the axis Ox, and a set of stringers 11B, forming longitudinal stiffeners parallel to the axis Ox. The hull structure also comprises one or more metal or composite sheets shaped according to the desired profile, and termed skin 11C. The skin 11C covers the mesh formed by the frames 11A and the stringers 11B.
The floor structure 12 comprises a set of crosspieces 12A and rails 12B. The rails 12B extend along the axis Ox, and serve for the attachment of furniture elements such as the seats. The rail 12C is an external rail, that is to say, a rail close to the hull structure, or in other words, close to the sidewalls of the aircraft. The crosspieces 12A extend along the axis Oy.
In the example shown in FIG. 1, the floor structure 12 is pressed against the hull structure 11 via the intermediary of stanchions 13 extending along the axis Oz.
In order to stabilize the floor structure 12, anti-crash connecting rods 14 extend in the plane (xOy). Each anti-crash connecting rod is an elongate rigid component, mounted fixed, at each one of its ends, to the floor structure on one hand, and to the hull structure on the other hand. In the example shown in FIG. 1, each anti-crash connecting rod 14 is attached at a first point 14A, to the external rail 12C, and at a second point 14B to a stringer 11B. The first point 14A is located close to the intersection between the external rail 12C and a crosspiece 12A. The second point 14B is located close to the intersection between a stringer 11B and a frame 11A. Each anti-crash connecting rod 14 extends diagonally, inclined relative to the axis Ox.
The anti-crash connecting rods 14 make it possible to hold the floor structure 12 substantially fixed relative to the hull structure 11, even in the event of sharp deceleration of the aircraft, and in particular in the event of the aircraft crashing. A crash can be either a crash proper or an abrupt landing of the aircraft, or an impact which approaches an abrupt landing in respect of the forces. In such a situation, the inertial force of the floor structure tends to move it away from the hull structure. In particular, the anti-crash connecting rods must be able to withstand an acceleration equal to 9 g along the axis Ox, towards the front of the aircraft (where g is the gravity of earth, equal to approximately 9.8 m/s−2). The force which acts on the anti-crash connecting rods is proportional to this acceleration and to the mass of the floor structure and the loads supported by the latter (furniture of the aircraft, passengers, etc.). In order to withstand such an acceleration, the anti-crash connecting rods have very large cross sections, and therefore a very high mass. An acceleration towards the front of the aircraft may also be called “deceleration.”